I am not concerned about the lighter tone, particularly for the first of three installments. Think about where this story is headed. By the end, our heroes will be in direct conflict with one another, and several main characters will die. How much more heartbreaking will it be to lose Thorin, Fili and Kili after three films with them than it was to lose Boromir after half a movie, or Theoden after two? Unlike FOTR, The Hobbit can take its time getting serious, and I think that's alright. In fact, a slower, gentler buildup through The Hobbit will probably enhance our experience of the LOTR trilogy, and of FOTR in particular.

On a related note: rewatching the LOTR trilogy recently, I was struck by the focus on Bilbo at the beginning and the end. When the elderly Bilbo declares at the end, "I'm quite ready for another adventure," I could see the young hobbit in the trailer running off with contract in hand. The whole saga is Bilbo's tale, in many ways. His courage, his pity, and his resilience set up the events that Frodo must endure (for which Bilbo is deeply sorry). Between The Hobbit and LOTR, we have a story about the effects of one generation's decisions on the generation that follows, for good or for ill.

Some of us have worried that The Hobbit film would be overwhelmed by LOTR's aesthetic, pacing, etc. I actually think that, if anything, LOTR will appear firmly grounded within the world of The Hobbit: with Bagshot row, Bilbo's trolls, Rivendell, Elrond, Galadriel, the wizards, Balin's tomb, Sting, Gollum, the Mithril rings, the Ring, Bilbo himself... Not until Rohan does LOTR move into truly new territory, and bring us finally out of the fairy tale into the world of Men.